Creating Message in JSON with JavaScript

In previous section you have studied about the JSON
in JavaScript's some basic concepts of creating a simple object and creating an
array of objects. Now we are going to discuss how to create a message with JSON
in JavaScript.

In this example of creating message in JSON with
JavaScript we have included "json2.js" file first. After this
we have created an object variable students which contains two array objects .
Again we have created an array object and pushed one array data into it. Message
is then created by converting array object to string by using the function "toJSONString()"
. Here is the example code of CreatingMessage.htm :

To run this example you need to include the JavaScript
file "json2.js" so that the functions defined for converting
objects to string and parse them can be done. This can be downloaded from http://www.json.org/json2.js

Here is the "json2.js" file code:

/*
json.js
2008-05-25

Public Domain
No warranty expressed or implied. Use at your own risk.
This file has been superceded by http://www.JSON.org/json2.js
See http://www.JSON.org/js.html
This file adds these methods to JavaScript:
array.toJSONString(whitelist)
boolean.toJSONString()
date.toJSONString()
number.toJSONString()
object.toJSONString(whitelist)
string.toJSONString()
These methods produce a JSON text from a JavaScript value.
It must not contain any cyclical references. Illegal values
will be excluded.

The default conversion for dates is to an ISO string. You can
add a toJSONString method to any date object to get a different
representation.

The object and array methods can take an optional whitelist
argument. A whitelist is an array of strings. If it is provided,
keys in objects not found in the whitelist are excluded.

string.parseJSON(filter)
This method parses a JSON text to produce an object or
array. It can throw a SyntaxError exception.

The optional filter parameter is a function which can filter and
transform the results. It receives each of the keys and values, and
its return value is used instead of the original value. If it
returns what it received, then structure is not modified. If it
returns undefined then the member is deleted.

Example:

// Parse the text. If a key contains the string 'date' then
// convert the value to a date.

This file will break programs with improper for..in loops. See
http://yuiblog.com/blog/2006/09/26/for-in-intrigue/

This file creates a global JSON object containing two methods: stringify
and parse.

JSON.stringify(value, replacer, space)
value any JavaScript value, usually an object or array.

replacer an optional parameter that determines how object
values are stringified for objects without a toJSON
method. It can be a function or an array.

space an optional parameter that specifies the indentation
of nested structures. If it is omitted, the text will
be packed without extra whitespace. If it is a number,
it will specify the number of spaces to indent at each
level. If it is a string (such as '\t' or '&nbsp;'),
it contains the characters used to indent at each level.

This method produces a JSON text from a JavaScript value.

When an object value is found, if the object contains a toJSON
method, its toJSON method will be called and the result will be
stringified. A toJSON method does not serialize: it returns the
value represented by the name/value pair that should be serialized,
or undefined if nothing should be serialized. The toJSON method
will be passed the key associated with the value, and this will be
bound to the object holding the key.For example, this would serialize Dates as ISO strings.
Date.prototype.toJSON = function (key) {
function f(n) {
// Format integers to have at least two digits.
return n < 10 ? '0' + n : n;
}
return this.getUTCFullYear() + '-' +
f(this.getUTCMonth() + 1) + '-' +
f(this.getUTCDate()) + 'T' +
f(this.getUTCHours()) + ':' +
f(this.getUTCMinutes()) + ':' +
f(this.getUTCSeconds()) + 'Z';
};

You can provide an optional replacer method. It will be passed the
key and value of each member, with this bound to the containing
object. The value that is returned from your method will be
serialized. If your method returns undefined, then the member will
be excluded from the serialization.

If the replacer parameter is an array, then it will be used to
select the members to be serialized. It filters the results such
that only members with keys listed in the replacer array are
stringified.

Values that do not have JSON representations, such as undefined or
functions, will not be serialized. Such values in objects will be
dropped; in arrays they will be replaced with null. You can use
a replacer function to replace those with JSON values.
JSON.stringify(undefined) returns undefined.

The optional space parameter produces a stringification of the
value that is filled with line breaks and indentation to make it
easier to read.

If the space parameter is a non-empty string, then that string will
be used for indentation. If the space parameter is a number, then
the indentation will be that many spaces.

JSON.parse(text, reviver)
This method parses a JSON text to produce an object or array.
It can throw a SyntaxError exception.

The optional reviver parameter is a function that can filter and
transform the results. It receives each of the keys and values,
and its return value is used instead of the original value.
If it returns what it received, then the structure is not modified.
If it returns undefined then the member is deleted.

Example:

// Parse the text. Values that look like ISO date strings will
// be converted to Date objects.

// If the string contains no control characters, no quote characters, and no
// backslash characters, then we can safely slap some quotes around it.
// Otherwise we must also replace the offending characters with safe escape
// sequences.

// The stringify method takes a value and an optional replacer, and an optional
// space parameter, and returns a JSON text. The replacer can be a function
// that can replace values, or an array of strings that will select the keys.
// A default replacer method can be provided. Use of the space parameter can
// produce text that is more easily readable.

var i;
gap = '';
indent = '';

// If the space parameter is a number, make an indent string containing that
// many spaces.

// In the second stage, we run the text against regular expressions that look
// for non-JSON patterns. We are especially concerned with '()' and 'new'
// because they can cause invocation, and '=' because it can cause mutation.
// But just to be safe, we want to reject all unexpected forms.

// We split the second stage into 4 regexp operations in order to work around
// crippling inefficiencies in IE's and Safari's regexp engines. First we
// replace the JSON backslash pairs with '@' (a non-JSON character). Second, we
// replace all simple value tokens with ']' characters. Third, we delete all
// open brackets that follow a colon or comma or that begin the text. Finally,
// we look to see that the remaining characters are only whitespace or ']' or
// ',' or ':' or '{' or '}'. If that is so, then the text is safe for eval.

// In the third stage we use the eval function to compile the text into a
// JavaScript structure. The '{' operator is subject to a syntactic ambiguity
// in JavaScript: it can begin a block or an object literal. We wrap the text
// in parens to eliminate the ambiguity.

j = eval('(' + text + ')');

// In the optional fourth stage, we recursively walk the new structure, passing
// each name/value pair to a reviver function for possible transformation.

return typeof reviver === 'function' ?
walk({'': j}, '') : j;
}

// If the text is not JSON parseable, then a SyntaxError is thrown.

throw new SyntaxError('JSON.parse');
}
};
}();
}

// Augment the basic prototypes if they have not already been augmented.
// These forms are obsolete. It is recommended that JSON.stringify and
// JSON.parse be used instead.

vev
December 27, 2011
correction in script
include json.js not json2.js

Lee
May 21, 2012
PHP
This is all great for retrieving the json stuff in the same page via jquery/javascript. It doesn't do a thing for someone trying to retrieve the json string in a php program invoked via ajax.

Pait
October 27, 2012
msCPQHLRRebea
Yup, that'll do it. You have my aprpeciation.